EP2093104A1 - Power supply method for an automobile headlight and headlight implementing this method - Google Patents

Abstract

The method involves electrically powering a light source (4) with voltage when the light source is in a route mode and powering the light source with another voltage when the light source is in a code mode, where the latter voltage is lower than the former voltage. Value of the former voltage is near or equal to nominal voltage of the light source, where the latter voltage is strictly lower than the nominal voltage. The voltages are constituted by pulse-width modulated signals. An independent claim is also included for an illuminating headlight for a motor vehicle, comprising a light source.

Description

The invention relates to a method for electrically powering a car projector lamp so that the lamp has both a luminance and a life time sufficient to be installed in a motor vehicle. The invention also relates to a lighting projector for a motor vehicle, wherein this method is implemented.

The invention has applications in the field of lighting for motor vehicles and, in particular, in the field of power supply lamps in vehicle lighting projectors.

• des feux de position, d'intensité et de portée faible ;
• des feux de croisement, ou codes, d'intensité plus forte et de portée sur la route avoisinant 70 mètres, utilisés essentiellement la nuit et dont la répartition du faisceau lumineux est étudiée pour ne pas éblouir le conducteur d'un véhicule venant en sens inverse ;
• des feux de route, avec une longue portée avoisinant les 200 mètres, qui sont utilisés pour éclairer la route au loin et permettre au conducteur d'appréhender la trajectoire du véhicule ;
• des feux anti-brouillard.

In the field of automotive lighting, there are different types of light projection devices among which we find essentially:

• position, intensity and low range lights;
• low beam, or codes, of higher intensity and range on the road of about 70 meters, used mainly at night and whose distribution of the light beam is studied not to dazzle the driver of a vehicle coming in the opposite direction ;
• high beams, with a long range of around 200 meters, which are used to illuminate the road in the distance and allow the driver to apprehend the trajectory of the vehicle;
• fog lights.

Currently, there are light projection devices, or projectors, which provide both the code function and the road function. These projectors are called dual-function or dual-mode projectors. They alternately provide code-mode lighting and road-mode lighting. Such a dual-function projector comprises a light source emitting identical lighting whatever the mode of operation (road or code). It generally comprises a removable cover capable of ensuring a cut-off of the light beam. This cover is, for example, a metal flap that can be in a first position or a second position. In the first position, the cache does not obscure the light beam produced by the light source, or lamp, of the projector. In the second position, the cache partially obscures the light beam produced by the projector lamp. In this second position, it is said that the cache performs a specific cut of the light beam, this specific cutoff corresponds to the cutoff of the light beam needed to obtain the code function. Thus, the lighting in code mode or in road mode differs in the presence or absence of the cut.

• la seconde position, appelée position d'occultation, dans laquelle il assure la coupure du faisceau lumineux, générant ainsi la fonction d'éclairage code, et
• la première position, appelée position neutre, dans laquelle le cache n'occulte pas le faisceau lumineux, générant alors la fonction d'éclairage de route, ou fonction route.

In most dual-function projectors, the removable cover is pivotable. It can thus take the two positions mentioned above, namely:

• the second position, called the occultation position, in which it ensures the breaking of the light beam, thus generating the code lighting function, and
• the first position, called neutral position, in which the cache does not obscure the light beam, thereby generating the road lighting function, or road function.

On the figure 1 an example of a motor vehicle headlight is shown. This projector 10 generally comprises a housing 1 closed by a protective glass 2. The projector 10 comprises, inside the housing, a lighting module 3, for example an elliptical module. The lighting module 3 comprises, in particular, a light source 4, also called a lamp, a reflector 5 adapted to reflect the light towards the protective glass, a lens 6 capable of diffusing light, a removable cover 7, and a light source. 8 power supply of the light source.

In current dual-function projectors, the light source can be a halogen light source. This halogen light source is generally powered by a fixed voltage, which depends on the light source used, the vehicle in which the light source is mounted and / or the country in which the vehicle will be sold. This fixed voltage is generally the nominal voltage of the light source. Indeed, a nominal voltage is specified by the lamp manufacturers for each type of light source. This nominal voltage is the supply voltage for which the operation of the light source is optimal.

To allow the projector to properly illuminate the road scene at the front of the vehicle, a light source must have good performance, that is to say a high power. The performance of a light source is mainly characterized by its flux and luminance. These performances, fluxes and luminances are functions of the voltage at the terminals of the light source. Thus, the higher the voltage across the light source, the higher the flux and the luminance. By way of example, considering the luminance: for a standard H9 type lamp, the luminance is of the order of 3400 cd / cm ² for a nominal voltage at the lamp terminals of 13.2 volts and 3150 cd. / cm ² for a voltage of 12.8 volts.

However, it is known to those skilled in the art that the higher the voltage at the terminals of the lamp, the longer the life of said lamp is low. In other words, the improvement in luminance is to the detriment of the life of the lamp. For example, with a voltage of 11.78 Volts, an H9 lamp has a life time approximately 4.4 times higher than that corresponding to its nominal voltage of 13.2 volts, which is, in this case, of the order of 250 hours

• une lampe à longue durée de vie, telle qu'une lampe H7 Long Life, qui offre une performance moyenne, avec une luminance de l'ordre de 2350 cd/cm², et une durée de vie longue (de l'ordre de 700 heures). Une telle lampe a l'inconvénient d'offrir un éclairage peu puissant, essentiellement en fonction route pour laquelle la luminance a un rôle très important.
  Ou
• une lampe très performante, telle qu'une lampe H9, qui offre une très bonne luminance (de l'ordre de 3400 cd/cm²) mais une durée de vie courte (de l'ordre de 250 heures). Une telle lampe présente l'inconvénient de devoir être changée fréquemment, ce qui entraîne bien sûr un coût supplémentaire pour le propriétaire du véhicule. La durée de vie d'une telle lampe peut être améliorée en diminuant la tension aux bornes de la lampe. Avec une tension d'alimentation, par exemple de 11,78 Volts, la durée de vie de la lampe est d'environ 1095 heures, mais sa luminance baisse à 2350 cd/cm², ce qui correspond à la luminance d'une lampe H7 Long Life. Une telle lampe avec une tension d'alimentation diminuée présente donc les mêmes performances de puissance qu'une lampe H7 Long Life.

It is therefore difficult at present to find a compromise between performance and service life. Car manufacturers must choose, for equipping a vehicle, between a long life lamp and a high luminance lamp. They must therefore choose between two types of lamp:

• a long-lasting lamp, such as a H7 Long Life lamp, which offers average performance, with a luminance of around 2350 cd / cm ² , and a long life (of the order of 700 hours). Such a lamp has the disadvantage of providing low-power lighting, essentially road function for which the luminance has a very important role.
  Or
• a very powerful lamp, such as a H9 lamp, which offers a very good luminance (of the order of 3400 cd / cm ² ) but a short life (of the order of 250 hours). Such a lamp has the disadvantage of having to be changed frequently, which of course leads to an additional cost for the vehicle owner. The life of such a lamp can be improved by decreasing the voltage across the lamp. With a supply voltage of, for example, 11.78 volts, the life of the lamp is approximately 1095 hours, but its luminance drops to 2350 cd / cm ² , which corresponds to the luminance of a lamp H7 Long Life. Such a lamp with a reduced supply voltage therefore has the same power performance as a H7 Long Life lamp.

To solve the disadvantages of the techniques described above, the invention provides a method in which a different supply voltage is applied across the light source, depending on the operating mode in which the projector is located. More precisely, when the headlamp is in road mode, the light source is supplied with a voltage close to the nominal voltage of said light source and, when the headlamp is in code mode, a voltage strictly lower than the nominal voltage is applied to the terminals. of the light source.

More specifically, the invention relates to a method of supplying a dual-mode automobile projector light source capable of alternately providing road-mode lighting and code-mode lighting, characterized in that the light source is electrically powered. with a first voltage when in road mode and with a second voltage when in code mode, the second voltage being lower than the first voltage.

Thus, since the proportion of operation of a projector in road mode is significantly lower than that of code mode operation on the one hand, the The lifetime of the light source is increased compared to full operation at nominal voltage and, on the other hand, the power of the light source in road mode is improved.

• la première tension à une valeur proche ou égale à une tension nominale de la source lumineuse.
• la seconde tension est strictement inférieure à la tension nominale de la source lumineuse.
• la première et la seconde tensions sont des signaux modulés en largeur PWM.
• le signal PWM correspondant à chaque tension est commandé par un contrôleur d'éclairage.
• le signal PWM correspondant à chaque tension est commandé par une carte électronique de régulation implantée dans le projecteur.

The method of the invention may include one or more of the following features:

• the first voltage at a value close to or equal to a nominal voltage of the light source.
• the second voltage is strictly lower than the nominal voltage of the light source.
• the first and second voltages are PWM width modulated signals.
• the PWM signal corresponding to each voltage is controlled by a lighting controller.
• the PWM signal corresponding to each voltage is controlled by an electronic control card installed in the projector.

• une source lumineuse associée à un module d'éclairage générant un faisceau lumineux,
• un cache amovible, et
• des moyens d'alimentation en tension de la source lumineuse,

caractérisé en ce que les moyens d'alimentation sont aptes à générer alternativement une première tension lorsque le projecteur est en mode route et une seconde tension, inférieure à la première tension, lorsque le projecteur est en mode code.The invention also relates to a lighting projector for a motor vehicle, comprising:

• a light source associated with a lighting module generating a light beam,
• a removable cache, and
• voltage supply means for the light source,

characterized in that the supply means are adapted to alternately generate a first voltage when the projector is in road mode and a second voltage, lower than the first voltage, when the projector is in code mode.

• les moyens d'alimentation de la source lumineuse consistent en un contrôleur d'éclairage.
• les moyens d'alimentation de la source lumineuse comportent un contrôleur d'éclairage associé à une carte électronique de régulation implantée dans le projecteur.
• la carte électronique comporte un composant MOS intelligent et/ou d'autres composants identiques capables d'assurer la fonction de régulation de la tension.
• les moyens d'alimentation de la source lumineuse comportent un contrôleur d'éclairage associé à une carte électronique de régulation implantée dans le projecteur, ladite carte pouvant être commandée par des signaux logiques et/ou des messages transitant sous forme numérique sur un bus.
• les moyens d'alimentation de la source lumineuse comportent un contrôleur d'éclairage associé à une carte électronique de régulation implantée dans le projecteur, ladite carte pouvant être commandée par des messages transitant sous forme numérique sur un bus autorisant une modification dynamique des première et seconde tensions aux bornes de la source lumineuse en fonction de différents profils de mission.

The projector of the invention may comprise one or more of the following features:

• the supply means of the light source consist of a lighting controller.
• the power supply means of the light source comprise a lighting controller associated with an electronic control card installed in the projector.
• the electronic card comprises an intelligent MOS component and / or other identical components capable of providing the voltage regulation function.
• the power supply means of the light source comprise a lighting controller associated with a control electronic card installed in the projector, said card being able to be controlled by logic signals and / or messages transiting in digital form on a bus.
• the power supply means of the light source comprise a lighting controller associated with a control electronic card located in the projector, said card being able to be controlled by messages transiting in digital form on a bus allowing a dynamic modification of the first and second Voltages at the terminals of the light source according to different mission profiles.

The invention further relates to a vehicle comprising a projector as described above.

• la figure 1, déjà décrite, représente schématiquement un projecteur de véhicule automobile classique;
• la figure 2 représente un tableau regroupant des exemples de valeurs de luminance et de durée de vie pour deux types de source lumineuse ;
• la figure 3 représente schématiquement un premier moyen d'alimentation électrique de la source lumineuse selon l'invention ; et
• les figures 4A, 4B, 4C et 4D représentent schématiquement différents moyens d'alimentation électrique de la source lumineuse selon l'invention.

The invention will now be described, without limitation, in relation to the following drawings:

• the figure 1 , already described, schematically shows a projector of a conventional motor vehicle;
• the figure 2 represents a table containing examples of luminance and lifetime values for two types of light source;
• the figure 3 schematically represents a first power supply means of the light source according to the invention; and
• the Figures 4A, 4B , 4C and 4D schematically represent different power supply means of the light source according to the invention.

The invention relates to a method for supplying the light source of a motor vehicle headlamp differently according to the mode of operation of the headlamp. In particular, the invention proposes to supply the light source with a voltage whose value is close to the nominal voltage indicated by the manufacturer of the light source, when the projector is in road mode. This voltage may, however, be chosen different from the nominal voltage of the manufacturer by the automotive manufacturer depending on the performance and / or lifetime that he wishes for its lighting function. The invention further proposes to supply the light source with a voltage strictly lower than the nominal voltage, when the projector is in code mode. Thus, in the invention, the road mode lighting and the code mode lighting are differentiated, not only by the presence or absence of the cut, but also by the luminance of the light beam emitted by the light source.

In the remainder of the description, reference will be made to the road and code modes of the headlight and to the road and code modes of the light source, provided that the light source is necessarily in the same mode as the headlamp.

It has been found, in the field of automotive lighting, that a headlamp operates approximately 95% of the time it is in operation, in code mode, that is to say in the mode where the dipped headlights are on.

In code mode, it is necessary for the projector to provide sufficient lighting with regard to safety requirements and regulatory requirements. Devices currently existing and regarded as honorable are developed to achieve such performance over a long life using H7 Long Life type lamps (called H7LL) or performance and life of the same order of magnitude.

The projector operates only 5% of its time in the road mode, that is, in the mode where the high beam is on. However, it is in road mode that it is necessary for the driver, the projector provides a powerful light, that is to say, the light source has a high performance. As a result, the light source must have a high luminance for only 5% of its operating time.

Taking into account this observation as well as the previously explained relation between the value of the voltage and the luminance level of a light source, the invention proposes to supply the light source of the projector with a voltage close to the nominal voltage. during the 5% of time when it operates in road mode and to supply said light source with a reduced voltage during the 95% of the time when the light source operates in code mode.

The nominal voltage is the voltage supplied by the manufacturer of the light source and considered to provide optimal operation of the light source. In the invention, the voltage applied when the light source is in the road mode may be the nominal voltage. This voltage may also be a voltage substantially less than, or greater than, the rated voltage. Indeed, in the invention, the voltage applied when the light source is in road mode is a voltage of sufficient value for the luminance of the light source to reach a level chosen by the car manufacturer. In the remainder of the description, the term "nominal voltage" will be understood as being a voltage close to or equal to the nominal voltage.

On the figure 2 a table showing examples of luminance and lifetime for different types of lamps at different voltage levels is shown. This table shows, in particular, the luminances and lifetimes of an H7LL lamp and an H9 lamp. With a lamp voltage of 12.8 volts, an H7LL lamp has a luminance of 2150 cd / cm ² and an H9 lamp has a luminance of 3150 cd / cm ² . When the voltage rises to 13.2 Volts, the luminance of H7LL increases to 2350 cd / cm ² and that of H9 to 3400 cd / cm ² . In this case, the life of H7LL is 700 hours and that of H9 is 250 hours.

If the supply voltage of the H9 lamp is reduced to 11.78 Volts, the luminance of H9 increases to 2350 cd / cm ² , which corresponds to the luminance of a H7LL lamp powered at 13.2V. On the other hand, the life of H9 increases to 1095 hours, which is even slightly longer than the life of an H7LL lamp. It is therefore understood that, with the method of the invention, the H9 lamp has performance and a lifetime at least identical to those of an H7LL lamp, when the lamp is in code mode, that is to say for 95% of the time. On the other hand, the H9 lamp retains its initial performance, ie high performance, when in the road mode, that is to say for 5% of the time. It is understood that over the entire operating life of a lamp H9, that is to say over 100% of the time, the life of a lamp is significantly improved.

d"où $$\mathrm{3}\mathrm{,}\mathrm{25}\mathrm{Ln}\frac{\mathrm{V}}{\mathrm{13}\mathrm{,}\mathrm{2}}\mathrm{=}\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}$$

$$\mathrm{Ln}\frac{\mathrm{V}}{\mathrm{13}\mathrm{,}\mathrm{2}}=\frac{1}{3,25}\times \mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}$$

$$\frac{\mathrm{V}}{\mathrm{13}\mathrm{,}\mathrm{2}}\mathrm{=}{\mathrm{e}}^{\frac{\mathrm{1}}{\mathrm{3}\mathrm{,}\mathrm{25}}\mathrm{\times }\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}}$$

$$\mathrm{V}=\mathrm{13}\mathrm{,}\mathrm{2}\times {\mathrm{e}}^{\frac{\mathrm{1}}{\mathrm{3}\mathrm{,}\mathrm{25}}\mathrm{\times }\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}}$$

$$\mathrm{V}=11,78$$

In the foregoing description, the supply voltage of 11.78 volts corresponds to the preferred embodiment of the invention. This supply voltage was determined so as to obtain, with a H9 lamp under wattage (that is to say receiving a reduced supply voltage at its terminals), the same luminance as a H7LL lamp at 13, 2V. It is known, in fact, in the field of automotive lighting, that the performance of the lamp varies in power 3.25 of the voltage at its terminals. The reduced voltage V of H9 was therefore determined from the luminance and the voltage across H7LL, as follows: $${\left(\frac{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">V</figure-callout>}}{\mathrm{13}\mathrm{,}\mathrm{2}}\right)}^{\mathrm{3}\mathrm{,}\mathrm{25}}\mathrm{=}\frac{\mathrm{2350}}{\mathrm{3400}}$$

from where $$\mathrm{3}\mathrm{,}\mathrm{25}\mathrm{Ln}\frac{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">V</figure-callout>}}{\mathrm{13}\mathrm{,}\mathrm{2}}\mathrm{=}\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}$$

$$\mathrm{Ln}\frac{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">V</figure-callout>}}{\mathrm{13}\mathrm{,}\mathrm{2}}=\frac{1}{3,25}\times \mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}$$

$$\frac{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">V</figure-callout>}}{\mathrm{13}\mathrm{,}\mathrm{2}}\mathrm{=}{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">e</figure-callout>}}^{\frac{\mathrm{1}}{\mathrm{3}\mathrm{,}\mathrm{25}}\mathrm{\times }\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}}$$

$$\mathrm{V}=\mathrm{13}\mathrm{,}\mathrm{2}\times {\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">e</figure-callout>}}^{\frac{\mathrm{1}}{\mathrm{3}\mathrm{,}\mathrm{25}}\mathrm{\times }\mathrm{Ln}\frac{\mathrm{2350}}{\mathrm{3400}}}$$

$$\mathrm{V}=11,78$$

It is known, moreover, that the life of the lamp varies, power 13, depending on the voltage at its terminals. It is thus possible to determine the lifetime D of the H9 lamp according to the method of the invention: $$\mathrm{D}\mathrm{=}{\left(\frac{\mathrm{13}\mathrm{,}\mathrm{2}}{\mathrm{17}\mathrm{,}\mathrm{78}}\right)}^{\mathrm{13}}=4,38l$$

• H9 dure 250 heures à 13,2V
• H9 fonctionne 5% du temps à 13,2V
• Il reste donc 250 - 5% = 250 - 12,5 = 237,5 heures de fonctionnement à tension nominale,
• Ce qui équivaut à 237,5 x 4,38 ≈ 1040 heures en tension réduite.

In the case of an H9 lamp, for a nominal voltage of 13.2V, the service life is as follows:

• H9 lasts 250 hours at 13.2V
• H9 works 5% of the time at 13.2V
• There remains 250 - 5% = 250 - 12.5 = 237.5 operating hours at nominal voltage,
• That equates to 237.5 x 4.38 ≈ 1040 hours in reduced voltage.

The H9 lamp thus has a total lifetime of 1040 + 12.5 = 1052.5 hours with performance multiplied by about 1.4 compared to a conventional halogen lamp such as an H7LL lamp.

With such a method of supplying an H9 lamp, it is possible to obtain a headlamp offering a maximum illumination of the order of 80 Lux for the high beam and of the order of 45 Lux for the dipped beam .

The method of the invention which has just been described can be implemented in a motor vehicle headlight such as that shown in FIG. figure 1 . According to the invention, the power supply means 8 are able to alternately supply a nominal voltage of the light source and a reduced voltage, depending on the operating mode in which the projector is located (code mode or road mode). In particular, the power supply means 8 are able to supply a first voltage close to or equal to the nominal voltage of the light source when said light source is in road mode; they are also able to provide a reduced voltage, a value predefined by the car manufacturer, when the light source is in code mode.

For this, the power supply means 8 of the projector can consist of a lighting controller located outside the projector and which can be integrated if necessary into another electronic box such as the "body controler", to control the power of the vehicle lamps. In this case, the light source is powered directly by the lighting controller of the vehicle, with a modulated signal in duration, called PWM (Pulse Width Modulation, in Anglo-Saxon terms). In code mode, the lighting controller supplies the light source with a PWM signal to regulate the average voltage across the light source to the preset reduced voltage value, for example 11.78V. In road mode, the lighting controller supplies the light source with a PWM signal to regulate the average voltage across the light source to the nominal voltage value, for example 13.2V. The PWM signal is a binary signal that can be equal to 1, which means that 100% of the current flows, ie 0, which means that 0% of the current flows.

On the figure 3 there is shown an example of an electronic circuit corresponding to the first embodiment of the supply means 8. In this figure, the supply means 8 consist of a lighting controller 81 which generates a first signal 82, called PWM _R and a second signal 83, called PWM _C , to the light source 4. The first signal 82 has a first pulse width corresponding to the voltage close to the nominal voltage. This first signal 82 is generated when the projector is in road mode. The lighting controller 81 generates, alternatively, a second signal 83 having a second pulse width corresponding to the reduced voltage. This second signal 83 is generated when the projector is in code mode.

Thus, in road mode, the light source 4 is powered by the power supply voltage V _ALIM of the width-modulated lighting controller with the ratio PWM _R (For the case where the PWM factor _R is equal to 1, the light source is powered directly by voltage V _ALIM 89). In code mode, the light source 4 is powered by the supply voltage V _ALIM of the width-modulated lighting controller with the PWM _C ratio. The duty cycle of the PWM signal _R is greater than that of the PWM signal _C , ie: RMS voltage (PWM _R )> RMS voltage (PWM _C ).

The car manufacturer can then choose the values of the voltages he wants to regulate, according to the mission profile of the vehicle. It can thus decide to feed differently the lamps of the vehicles according to the countries and the requirements of lifetime and / or luminance. In this embodiment, the voltage values are programmed directly into the lighting controller software.

In a second embodiment of the projector, the regulation of the voltage is performed by an electronic control card PWM signal in the light source. This card, located in the projector, can be separated or be part of a smart lighting controller internal to the projector in the case where other functions are required (for example for daytime lighting and / or direction indicators to leds or in the case of devices "with rotating headlamps").

On the Figure 4A , there is shown a first example of an electronic circuit corresponding to the second embodiment of the supply means 8. On this Figure 4A , the power supply means 8 comprise a lighting controller external to the projector 84 which generates a first signal 86, called V _ROUTE and a second signal 87, called V _CODE . The signal V _ROUTE is a signal coming directly from the voltage VAlim modulated by the PWM signal (PWM may be optionally equal to 1), the signal V _CODE is itself a binary signal which can take the value 0 or 1.

The signals V _ROUTE and V _CODE are transmitted to the electronic card 85. This electronic card 85 is located in the projector. This electronic card 85 comprises, in particular, an intelligent MOS component, for example a Smart MOS 88, having the particularity of cutting the current flowing in the light source to provide a PWM signal.

• soit le circuit laisse passer toute la tension d'alimentation V_ALIM 89 dans la source lumineuse 4, ce qui équivaut à un signal PWM à 1 ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à V_ALIM;
• soit le circuit dispose d'une régulation intrinsèque qui module le courant d'alimentation à un taux de modulation PWM prédéfini, c'est-à-dire à PWM_R; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à V_PWMR

The different cases that can occur, according to the values of V _ROUTE and V _CODE , are grouped in the table of the Figure 4B . In road mode, that is to say when the signal code V _CODE is 0, two cases are possible:

• either the circuit passes all the supply voltage V _ALIM 89 in the light source 4, which is equivalent to a PWM signal to 1; the voltage V _LAMP at the terminals of the light source 4 is then equal to V _ALIM ;
• either the circuit has an intrinsic regulation that modulates the power supply current to a predefined PWM modulation rate, that is to say PWM _R ; the voltage V _LAMP at the terminals of the light source 4 is then equal to V _PWMR

• lorsque PWM_R est à 1, le circuit génère un signal PWM fixe qui module le courant de la source lumineuse ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à la tension du signal PWM_C, V_PWMC;
• lorsque PWM_R est différent de 1, le circuit génère un signal PWM qui se synchronise sur un des flans du signal modulé d'alimentation et regénère un signal de facteur PWM différent qui fait baisser la tension efficace aux bornes de la source lumineuse ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à la tension du signal PWM_C, V_PWMC.
  Comme précédemment, dans ce mode deuxième mode de réalisation, le constructeur automobile peut choisir les valeurs des tensions qu'il veut réguler, en fonction du profil de mission du véhicule. Par contre, dans ce mode de réalisation, les valeurs des tensions doivent être prévues lors de l'implantation de la carte électronique.
  Dans un troisième mode de réalisation, les ordres relatifs aux modes de fonctionnement Code et Route peuvent être envoyés sous forme de messages binaires 0 ou 1 (dans ce cas il y a 2 entrées de commandes) sous forme de messages transitant sur un bus, par exemple sous protocole LIN ou CAN.
  La carte électronique 90, dans le projecteur 10, comporte, dans ce cas, un dispositif logique 91, par exemple à base de microcontrôleur, capable de décrypter les messages et piloter en conséquence la partie relative à la commande PWM de la source lumineuse.
  Dans le cas de la figure 4C, les signaux Code et Route issus du contrôleur d'éclairage 92, externe au projecteur, sont binaires ; la logique de commande de la source lumineuse est décrite dans le tableau de la figure 4C :
  VRoute =0, V Code =0 - aucun courant ne circule dans la source lumineuse
  VRoute= 1, V Code =1 -aucun courant ne circule dans la source lumineuse
  VRoute= 1, V Code =0 - Mode route
• soit le circuit laisse passer tout le courant d'alimentation V_ALIM 89 dans la source lumineuse 4, ce qui équivaut à un signal PWM à 1 ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à V_ALIM
• soit le circuit dispose d'une régulation intrinsèque qui module le courant d'alimentation à un taux de modulation PWM prédéfini, c'est-à-dire à PWM_R; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à V_PWMR
  VRoute= 0, V Code =1 - Mode code

In code mode, the V _CODE signal is at 1. The circuit can then operate in two ways:

• when PWM _R is 1, the circuit generates a fixed PWM signal which modulates the current of the light source; the voltage V _LAMP at the terminals of the light source 4 is then equal to the voltage of the PWM signal _C , V _PWMC;
• when PWM _R is different from 1, the circuit generates a PWM signal which synchronizes on one of the blanks of the modulated supply signal and regenerates a signal of different PWM factor which lowers the effective voltage across the light source; the voltage V _LAMP at the terminals of the light source 4 is then equal to the voltage of the PWM signal _C , V _PWMC .
  As previously, in this second embodiment mode, the car manufacturer can choose the values of the voltages he wants to regulate, depending on the mission profile of the vehicle. In contrast, in this embodiment, the values of the voltages must be provided during the implementation of the electronic card.
  In a third embodiment, the commands relating to the Code and Route operating modes can be sent in the form of binary messages 0 or 1 (in this case there are 2 command entries) in the form of messages transiting on a bus, for example example under LIN or CAN protocol.
  The electronic card 90, in the projector 10, comprises, in this case, a logic device 91, for example based on a microcontroller, capable of decrypting the messages and control accordingly the portion relating to the PWM control of the light source.
  In the case of figure 4C the Code and Route signals from the lighting controller 92, external to the projector, are binary; the control logic of the light source is described in the table of the figure 4C :
  VRoute = 0, V Code = 0 - no current flowing in the light source
  VRoute = 1, V Code = 1 -no current flows in the light source
  VRoute = 1, V Code = 0 - Route Mode
• either the circuit passes all the supply current V _ALIM 89 in the light source 4, which is equivalent to a PWM signal to 1; the voltage V _LAMP at the terminals of the light source 4 is then equal to V _ALIM
• either the circuit has an intrinsic regulation that modulates the power supply current to a predefined PWM modulation rate, that is to say PWM _R ; the voltage V _LAMP at the terminals of the light source 4 is then equal to V _PWMR
  VRoute = 0, V Code = 1 - Code mode

• lorsque PWM_R est à 1, le circuit génère un signal PWM fixe qui module le courant de la source lumineuse ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à la tension du signal PWM_C, V_PWMC;
• lorsque PWM_R est différent de 1, le circuit génère un signal PWM qui se synchronise sur un des flans du signal modulé d'alimentation et régénère un signal de facteur PWM différent qui fait baisser la tension efficace aux bornes de la source lumineuse ; la tension V_LAMPE aux bornes de la source lumineuse 4 est alors égale à la tension du signal PWM_C, V_PWMC.

The circuit can then operate in two ways:

• when PWM _R is 1, the circuit generates a fixed PWM signal which modulates the current of the light source; the voltage V _LAMP at the terminals of the light source 4 is then equal to the voltage of the PWM signal _C , V _PWMC;
• when PWM _R is different from 1, the circuit generates a PWM signal which synchronizes on one of the blanks of the modulated supply signal and regenerates a different PWM factor signal which lowers the effective voltage across the light source; the voltage V _LAMP at the terminals of the light source 4 is then equal to the voltage of the PWM signal _C , V _PWMC .

As previously, in this third embodiment, the car manufacturer can choose the values of the voltages he wants to regulate, according to the mission profile of the vehicle. In this embodiment, the values of the voltages must also be provided during the implementation of the electronic card.

In a fourth embodiment, the commands relating to the Code and Route operating modes can be sent in the form of messages transiting on a bus 96, for example under the LIN or CAN protocol.

The electronic card 93, in the projector 10, then comprises a logic device 95, often based microcontroller, able to decrypt the messages and control accordingly the portion relating to the PWM control of the light source.

In the case of figure 4D , Code and Route signals from the lighting controller are messages coded under the manufacturer's imposed protocol. The programming of the microcontroller 95 associated with the control electronics of the card allows to control the lamps according to the modes code and road with the factors PWM _r and PWM _c adequate.

In this embodiment, the values of the voltages (PWM report values) can be variable and controlled as needed by the body controler directly according to the profile desired by the manufacturer.

Claims (13)

A method of supplying a dual-mode automotive projector light source capable of alternately providing road-mode lighting and code-mode lighting,
characterized in that the light source (4) is electrically powered with a first voltage (82, 86) when in the road mode and with a second voltage (83, 87) when in code mode, the second voltage being lower than the first voltage. Power supply method according to claim 1, characterized in that the first voltage has a value close to or equal to a nominal voltage of the light source. Power supply method according to claim 2, characterized in that the second voltage is strictly lower than the nominal voltage of the light source. Power supply method according to one of claims 1 to 3, characterized in that the first and second voltages are Width Modulated (PWM) signals. Power supply method according to claim 4, characterized in that the PWM signal corresponding to each voltage (83, 82) is controlled by a lighting controller (81). Power supply method according to claim 4, characterized in that the PWM signal corresponding to each voltage (86, 87) is controlled by an electronic control card (85) located in the projector. Lighting projector (10) for a motor vehicle, comprising: a light source (4) associated with a lighting module (3) generating a light beam, a removable cover (7), and means (8) for supplying voltage to the light source, characterized in that the supply means are adapted to alternately generate a first voltage (82, 86) when the headlamp is in road mode and a second voltage (83, 87), lower than the first voltage, when the headlamp is in code mode. Projector according to claim 7, characterized in that the means (8) for supplying the light source consist of a lighting controller (81). Projector according to claim 7, characterized in that the means (8) for supplying the light source comprise a lighting controller (84) associated with an electronic control card (85) located in the projector. Projector according to claim 9, characterized in that the electronic card comprises an intelligent MOS component (88). Projector according to Claim 7, characterized in that the means (8) for supplying the light source comprise an illumination controller (94) associated with an electronic control card (93) located in the projector, said card being able to be controlled by logic signals and / or messages transiting in digital form on a bus (96). Projector according to claim 7 or 11, characterized in that the means (8) for supplying the light source comprise a lighting controller (94) associated with an electronic control card (93) located in the projector, said card can be controlled by messages passing in digital form on a bus (96) allowing a dynamic modification of the first and second voltages across the light source according to different mission profiles. Motor vehicle, characterized in that it comprises a headlamp according to any one of Claims 7 to 12.

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